﻿using System;
using System.Collections.Generic;
using System.Text;

namespace Apewer
{

    /// <summary></summary>
    public class ChinaUtility
    {

        private static bool CheckIdCode18(string idCode18)
        {
            // GB11643-1999
            if (string.IsNullOrEmpty(idCode18) || idCode18.Length != 18) return false;
            var code = idCode18;

            // 数字。
            var n = 0L;
            if (long.TryParse(code.Remove(17), out n) == false) return false;
            if (n < Math.Pow(10, 16)) return false;
            if (long.TryParse(code.Replace('x', '0').Replace('X', '0'), out n) == false) return false;

            // 省份。
            var address = "11x22x35x44x53x12x23x36x45x54x13x31x37x46x61x14x32x41x50x62x15x33x42x51x63x21x34x43x52x64x65x71x81x82x91";
            if (address.IndexOf(code.Remove(2)) < 0) return false;

            // 生日。
            var birth = code.Substring(6, 8).Insert(6, "-").Insert(4, "-");
            var time = new DateTime();
            if (DateTime.TryParse(birth, out time) == false) return false;

            // 校验码。
            var cc = "10x98765432".ToCharArray();
            var wi = "7,9,10,5,8,4,2,1,6,3,7,9,10,5,8,4,2".Split(',');
            var ai = code.Remove(17).ToCharArray();
            var sum = 0;
            for (int i = 0; i < 17; i++)
            {
                sum += int.Parse(wi[i]) * int.Parse(ai[i].ToString());
            }
            var y = sum % 11;
            if (cc[y] != code[17]) return false;

            return true;
        }

        private static bool CheckIdCode15(string idCode15)
        {
            if (string.IsNullOrEmpty(idCode15) || idCode15.Length != 15) return false;
            var code = idCode15;

            // 数字。
            var n = 0L;
            if (long.TryParse(code, out n) == false || n < Math.Pow(10, 14)) return false;

            // 省份。
            var address = "11x22x35x44x53x12x23x36x45x54x13x31x37x46x61x14x32x41x50x62x15x33x42x51x63x21x34x43x52x64x65x71x81x82x91";
            if (address.IndexOf(code.Remove(2)) == -1) return false;

            // 生日。
            var birth = code.Substring(6, 6).Insert(4, "-").Insert(2, "-");
            var time = new DateTime();
            if (DateTime.TryParse(birth, out time) == false) return false;

            return true;

        }

        /// <summary></summary>
        public static bool CheckIdCode(string idCode)
        {
            if (string.IsNullOrEmpty(idCode)) return false;
            if (idCode.Length == 18) return CheckIdCode18(idCode);
            if (idCode.Length == 15) return CheckIdCode15(idCode);
            return false;
        }

    }

}
